A team of chemists from Ludwig Maximilian University of Munich (LMU) in Germany has developed a non-toxic alternative to colored smoke.

Used in day-time fireworks, smoke bombs, military smoke signals, fashion shows and advertising light effects, for instance, colored smoke can release toxic by-products into the environment, according to the researchers. As such, the LMU chemists, in collaboration with the U.S. Department of Defense’s Strategic Environmental Research and Development Program, have devised a non-toxic alternative by removing the primary ingredient in colored smoke.

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To achieve a non-toxic alternative to colored smoke, LMU chemists removed potassium chlorate from common colored smoke formulations. Reportedly, the combination of organic substances responsible for the colors in colored smoke and potassium chlorate results in carcinogenic polychlorinated compounds. Consequently, the chemists replaced potassium chlorate with non-toxic nitrogen-rich salt guanidinium-5,5'-azotetrazolate.

Mixed with organic dyes that behave as coloring agents, the halogen-free mixture reportedly prevents the production of toxic by-products while also producing a range of colors including blue, white, violet, red, yellow and green.

The research appears in the journal Angewandte Chemie.